1. Field of the Invention
This invention relates generally, as indicated, to an expandable tire building drum and especially to a tire casing finishing drum for small diameter tires such as radial aircraft tires. During building of tires of this type a relatively small diameter annular band of reinforcing plies is placed over the drum requiring a small diameter of the drum in the retracted condition. The band is initially expanded after which the beads are placed and the drum expanded to seat the beads in the bead pockets. Because of the number of reinforcing plies in the annular band, substantial force is required to expand the band and seat the beads. Also the size of the bead pockets must be sufficient to accommodate the substantial number of plies wrapped around the beads.
2. Description of the Prior Art
Tire building drums used heretofore for passenger tires have not been suitable for building radial aircraft tires because the air pressure actuated cam mechanism has not provided sufficient force to expand the casing and seat the beads. Where links have been used to expand a tire building drum, separate sets of links have been required to expand the center segments of the drum and the bead supporting fingers at the shoulders of the drum. This mechanism has been satisfactory for relatively large diameter tires; however, it is not usable with a small diameter tire of the radial aircraft type where the bead portions are so large there is no room for placing the expanding and contracting linkage under the bead supports.